The invention relates to a feeder insert for use in a mold utilized during pouring of metals, with a feeder body made of an exothermic and/or insulating material and having a feed volume, whereby the feed body is provided with an inner space, as the feed volume, delimited by side walls and a top portion, and in the base region of the feeder body a feed opening is formed as a communication to the hollow mold space.
A feeder insert having the aforementioned features is described in DE 196 42 838 A1. The feeder body, which has a closed inner space in its top portion, as a feed volume, can be placed, during the molding, upon the mold surface of the mold. During the molding of the feeder insert, the problem exists that the molding pressure, which acts upon the mold sand, and hence also upon the feeder body, can lead to damage of the feeder body.
To eliminate this problem, the company Chemex GmbH Has proposed and used a feeder insert, designated “telescopic feeder”, according to which the feeder body is comprised of two components that are displaceable relative to one another and together form the feed volume. In this connection, the lower portion of the feeder body, which can be placed upon the mold surface, is open at the top and is spanned from above by a second, bell-shaped part of the feeder body, whereby when molding pressure occurs the parts are pushed into one another and for this purpose the outer diameter of the lower part, and the inner diameter of the upper, bell-shaped part, must be coordinated with one another in an exactly fitting manner.
The feeder insert, which has become known through use, has the drawback that the fines or rubbed-off material that results when the upper and lower parts of the feeder inserts are pushed into one another can fall into the feed volume and when the mold is poured off can come into contact with the liquid metal, so that impurities in the molten metal can result. A further drawback is that the exact size of the feed volume of the molded feeder insert defined by the two parts of the feeder insert is determined by the extent to which the upper and lower parts of the feeder insert are pushed into one another, so that no reliable statement about the size of the feed volume of the molded feeder insert can be made. This makes the design of the insert, and the selection of the size of the necessary feeder insert, difficult.
It is therefore an object of the present invention to improve a feeder insert having the aforementioned features in such a way that despite maintaining a uniform, closed feed volume in the interior of the feeder insert, protection of the feeder insert against the effect of molding pressure is provided.